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Concept
Seam bowling
Résumé
Seam bowling is a bowling technique in cricket whereby the ball is deliberately bowled on to its seam, to cause a random deviation when the ball bounces. Practitioners are known as seam bowlers or seamers.
Seam bowling is a form of fast bowling, although the bowling speeds at which seam can be a factor include medium-pace bowling. Although there are specialist seamers that make deliberate use of off cutter and leg cutter at the expense of bowling slower than regular fast bowlers, most bowlers employ the seam to some effect and so the terms "seamer" and "fast bowler" are largely synonymous. This was far less the case in the past, even the recent past. Bowlers such as Tom Cartwright and Derek Shackleton bowled seamers at a pace in the low 70mphs and were very successful due to their mastery of control and variation.
A cricket ball is not a perfect sphere. The seam of the ball is the circular stitching which joins the two halves of the cricket ball. Hence, the seam joining the pieces of leather is circumferential and the stitching is noticeably raised. If the ball is bowled in such a way that the seam hits the pitch when it bounces, this irregularity can cause the ball to deviate sideways in its path. It may move in any direction, or just go straight. The batsman has to see how the ball moves after pitching to select his shot.
In order to achieve this effect, a seam bowler usually delivers the ball with the seam held upright, with rotation about a horizontal axis. This keeps the seam aligned vertically as it travels towards the batter, making it likely that the ball will bounce with the seam on the pitch. Consistently hitting the seam is not as easy as it sounds. The seam has to be held upright between the index finger and the middle finger at the time of the delivery of the ball and, most importantly, the wrist has to be dead straight when the ball is delivered. The seam and wrist position of Australia's Glenn McGrath are arguably a perfect example.
Source officielle
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